Re: [f2fs-dev] [PATCH] generic/064: allow 50 extents on F2FS after fcollapse
Christoph Hellwig <[email protected]>
| Newsgroups | net.sourceforge.lists.linux-f2fs-devel,org.kernel.vger.fstests |
|---|---|
| Message-ID | <[email protected]> |
On Mon, Jun 22, 2026 at 07:04:38AM +0000, Jan Prusakowski wrote: > On F2FS, generic/064 fails with "extents mismatched before = 1 after = > 50" following multiple fcollapse (collapse range) operations. > > To ensure crash consistency and checkpoint integrity, F2FS forbids > in-place SSR (Summary Standalone Replacement) overwrites on valid > checkpointed blocks. When collapse range shifts blocks, F2FS allocates > new data pages in LFS mode (out-of-place log writes). As a result, > sequential collapse range calls rewrite shifted blocks at new log > locations, intentionally leaving the file with 50 extents. This sounds odd. The test allocates a contigous range and then just does insert/collapse on it, which should not lead to any new data block allocations. Given that the test works fine on zoned XFS and btrfs with strict out of place write policies we know it does not require overwriting blocks to work as well. So I think something is fishy in f2fs if needs to allocate data blocks here. _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel